#include <bits/stdc++.h>

using namespace std;
using ll = long long;

void solve()
{
    int n;
    cin >> n;
    vector<double> bar(n);
    for (int i = 0; i < n; i++)
    {
        double x;
        cin >> x;
        bar[i] = x / 2.0;
    }
    if (n == 1)
    {
        cout << "0.00";
        return;
    }
    else if (n == 2)
    {
        printf("%.2f", bar[0] + bar[1]);
        return;
    }
    sort(bar.begin(), bar.end());
    double sum = bar[0] + bar[1];
    for (int i = 2; i < n; i++)
        sum += 2 * bar[i];
    printf("%.2f", sum);
}

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int t = 1;
    while (t--)
    {
        solve();
    }
    return 0;
}